1. Field of the Invention
This invention relates to a magnetic transducer head and, more particularly, to a composite type magnetic transducer head wherein the gap defining region of the head is formed of thin layers of metallic magnetic material.
2. Description of the Prior Art
In magnetic recording and/or reproducing apparatus, such as video tape recorders (VTRs), the recent tendency has been toward increasing the signal density of the recording medium. In order to increase the recorded signal density, so-called metal powder tapes and so-called metallized magnetic tapes with high coercive force (H.sub.c) are being used in increasing numbers. The metal powder tapes make use of powders of ferromagnetic metals such as iron, cobalt or nickel, or alloys thereof, while the so-called metallized tapes utilize a ferromagnetic metallic material coated on a film substrate by means of vapor deposition. Because of the high coercivity of these types of magnetic recording media, a high saturation magnetic flux density (B.sub.s) is required of the magnetic core material of the magnetic transducer head, particularly for a head utilized for signal recording operation. With the ferrite magnetic material predominantly used in magnetic recording, the saturation magnetic flux density is rather low, while a metallic magnetic material such as Permalloy presents a problem in that it has a lower wear resistance.
With the above-described tendency toward increasing the recorded signal density, it is desirable to make use of a narrow record track width on the magnetic recording medium, and for this purpose, it is necessary to have a magnetic transducer head coupling gap with a corresponding narrow lateral dimension.
In seeking to meet such requirements, a composite type magnetic transducer head has been previously developed in which a ferromagnetic metallic layer is deposited on a non-magnetic substrate, for example, of a ceramic material, with the thickness of the deposited layer corresponding to the record track width. This type of magnetic transducer head, however, presents a high magnetic reluctance for high frequency signal components because the entire magnetic signal flux path in the head is formed by the low resistivity ferromagnetic metallic layer. Furthermore, since the metallic magnetic layer is produced by physical vapor deposition with its characteristic slow deposition rate, the requirement that the thickness of the deposited layers must equal the track width can lead to a relatively long processing time and consequent materially increased production cost.
A composite type magnetic transducer head is also known in the art in which magnetic core elements are formed of ferromagnetic oxides such as ferrite, and ferromagnetic metallic layers are applied to confronting surfaces of the core elements for defining the transducer gap. However, in this case the path of magnetic flux and the broad surfaces of the metallic magnetic layers are disposed at right angles to each other, and playback output may be lowered because of the resulting eddy current loss. Also, a pseudo gap is produced at the interface between each of the ferrite magnetic core elements add the associated metallic magnetic layer, with a resulting detriment to a desired uniformity of playback frequency response.